US3056120A

US3056120A - Supervised condition detection and alarm apparatus

Info

Publication number: US3056120A
Application number: US55572A
Authority: US
Inventors: John W Mobarry
Original assignee: Honeywell Inc
Current assignee: Honeywell Inc
Priority date: 1960-09-12
Filing date: 1960-09-12
Publication date: 1962-09-25
Anticipated expiration: 1979-09-25

Description

ARATUS Sept. 25, 1962 J. w. MOBARRY SUPERVISED CONDITION DETECTION AND ALARM APP Filed Sept. 12. 1960 INVENTOR. JOHN w. MOBARRY BY ATTORNEY United States Patent ce 3 056 120 SUPERVISED CONDITIDN DETECTION AND ALARM APPARATUS John W. Mobarry, Edina, Minm, assignor to Minneapolis- This invention relates generally to electrical signaling systems and more specifically to electrical alarm circuits which are responsive to the occurrence of a dangerous condition to advise supervisory personnel of this condition. Apparatus of this general type may be used in fire, burglary, or any other application where it is desired to notify personnel in time for them to take precautionary measures.

In applications where human life is at stake, it is an absolute requirement that the signaling system employed be highly reliable. Because of this reliability requirement, the systems disclosed in the prior art tend to be quite complex and expensive thereby pricing this system out of the reach of the average home owner. The alarm circuit of the present invention is relatively simple in form and quite inexpensive. Notwithstanding these advantages, no sacrifice is made in the reliability requirements deemed to be so necessary.

The alarm system of my invention is arranged to provide an audible and/or visual indication upon occurrence of a dangerous condition to which it is responsive. As mentioned above, this may, for example, be an over temperature produced by a fire, or any other occurrence where it is desirable to notify supervisory personnel such that appropriate action may be taken. Additionally, provision is made in my alarm system to give an indication, either audible or visual, to supervisory personnel in the event that a fault such as a short circuit or open circuit has occurred somewhere in the system. Furthermore, there is provided in my system a self-contained auxiliary source of power which becomes operative to maintain the system in a standby condition in the event of a power failure, and to cause the alarm to sound in the event that the dangerous condition arises during the interval that the power has failed.

Included in my signaling system is a differential relay having switch means associated therewith. When the circuit is in its standby condition, the switch means are in a first position in which both the main alarm and the fault indicator are inoperative. Upon the occurrence of the dangerous condition, the balance condition of this relay is disturbed so as to cause the switch means associated therewith to be moved to a second or alarm position thereby allowing current to flow through said mainalarm causing it to operate. Furthermore, the circuits are designed such that a fault occurring in the system is effective to cause an unbalance of the relay such that its associated switch means is moved to still a third position in which the fault indicating alarm is energized.

It is accordingly ,an object or" the present invention to provide an improved means for giving an alarm at a central location upon the actuation of distributed detector means, and also to provide means whereby a break or short circuit fault in the system may be signaled.

It is another object of my invention to provide an alarm system which is both reliable and inexpensive.

Still another object of my invention is to provide an alarm system which remains operative even when a failure of this main source of power has occurred.

Still other objects of the present invention will be hereinafter pointed out in the accompanying specification and claims and shown in the drawing which by way of 3,056,120 Patented Sept- 25, 1962 2 illustration shows the preferred embodiment of the invention.

Referring now to the schematic diagram shown in the drawing, there is illustrated a transformer 10 having a primary winding 12 and a secondary winding 14. Primary winding 12 is adapted to be connected to a convenient source of alternating current potential, such as a volt 60 cycle source. Transformer 10* is effective to step down this voltage to a value suitable for use with the alarm. For example, the voltage appearing across

terminals

16 and 18 of the secondary winding 14 may be approximately 15 volts. Connected between the

terminals

16 and 18, i.e., directly across the secondary winding 14 is a power failure relay 20 which operates a plurality of

contact arms

20m, 20b, and 200. The operation of the power failure relay 20 will be described more fully hereinbelow, but for now it is suflicient to say that in the event of a power failure the power failure relay and its associated contacts are operative to switch an auxiliary source of power into the circuit and to sound a trouble alarm which will indicate this fault to the occupant of the premises where the apparatus is installed.

Continuing now with a description of the circuit layout, a conductor 22 connects the secondary winding terminal 16 to a contact 24 of the power failure relay 20. A conductor 26 connects the switch arms 20a and 20b to the

junctions

28, 30, 32, and 36 and to the switch arm 38 of a single pole double throw manual silencing switch 40. A conductor 42 is used to connect the sec ondary winding terminal 18 to the

junctions

44, 46 and 48 and to the

switch arms

50a, 50b, and 500 of an alarm relay 50. Connected between the

junctions

28 and 32 on conductor 26 and the junction 48 on conductor 42 is a balance circuit comprising a pair of current limiting

resistors

52 and 54, the two

coils

56 and 58 of a balanced relay, and a balancing potentiometer 60.

When normal line voltage is applied to the primary winding 12 of transformer 10, the power failure relay 20 is energized thereby completing a circuit path which may be traced through conductor 22, contact 24, switch arm 20a and conductor 26 to the junction 28. At junction 28, the current divides with approximately one-half of the total current flowing through the resistor 52, the balanced relay coil 56 and a portion of the balancing potentiometer to the junction 48 and the other half of the current flowing through a resistor 54, relay coil 58 and the other portion of the balancing potentiometer to junction 48. At junction 48 the current again combines and flows through the conductor 42 back to the sec ondary winding terminal 18. 'Equality of current flow through the two coils of the balanced relay is obtained by initially adjusting the position of the wiper arm 62 of the balancing potentiometer 60.

The

balanced relay coils

56 and 58 are arranged to operate a common armature 64. Armature 64 is shown as being rotatably mounted with respect to a pivot or fulcrum 66. The armature 64 is provided with a pair of

contacts

68 and 70 located on opposite sides of the fulcrum 66. When the signaling circuit of this inven-' tion is in its standby condition, i.e., the condition which exists when the system is free from faults and no dangerout condition is present, the armature 64 is in the position illustrated. When the balance circuit becomes unbalanced due either to the occurrence of a dangerous condition or due to a system fault the armature 64 is rotated either in the counterclockwise direction or the clockwise direction about fulcrum 66 depending upon which of the balanced relay coils 56 M58 receives a greater portion of the current. Because a conductor 72 connects the armature 64 to the junction 48 which, 'in turn, is connected by means of conductor 42 to the secondary winding terminal 18, a counterclockwise rotation of the armature 64 is effective to complete a circuit which may be traced from the secondary winding terminal 16 through conductor 22, contact 24, switch arm 2011, conductor 26, the alarm relay 50, and a contact 74 which is arranged to mate with contact 68. In a similar manner, a clockwise rotation of the armature 64 about fulcrum 66 completes the circuit between contact 70 and contact 76 so that a current can flow through the

conductors

22, 26, the switch arm 38 of single pole double throw switch 40, a conductor 78, a fault indicating alarm 80, a conductor 82, through the armature 64 and the conductor 72, and conductor 42 back to the secondary winding terminal 18. The current flowing through this last mentioned path is effective to energize the fault alarm 80.

Connected directly in parallel with the resistor 52 in the balanced circuit is a main alarm 84. Connected directly in parallel with the resistor 54, i.e., between the

conductors

86 and 88, are a plurality of detector means 90 and a termination or end of line resistor 92. The

conductors

86 and 88 pass through the areas of the premises to be protected and one or more detector means 90 is provided for each separate area. Detectors 90 are illustrated as being of the normally open contact type which when exposed to a dangerous condition become closed.

In order to supply energy to the circuit in the event of a failure of the line voltage, a battery source 94 is connected between the junction 44 on conductor 42 and a contact 96 which cooperates with the power failure relay switch arm b. The potential appearing at the junction 32 is normally applied through the conductor 26 and the single pole double throw manual silencing switch I to the fault alarm 80. When the switch is thrown from the position shown to its opposite position, a lamp 98 is inserted in the circuit between the

junctions

36 and 44.

In completing the description of the circuit arrangement, a conductor 100 connects the junction 46 on conductor 42 to the switch arm 200 of the power failure relay. Contact 102 which is associated with the switch arm 20c is connected by means of a conductor 104 to a junction 106 which is the common point between the conductor 82 and a conductor 108. Conductor 108 connects the junction 106 to a contact 110 which cooperates with the switch arm a of the alarm relay 50. A conductor 112 is used to connect a contact 114, which is associated with the switch arm 50c, to one side of the main alarm 84. Also shown in the drawing is a conductor 116 which connects one side of the alarm relay 50 to the balanced relay contact 74 and to a contact 118 which is associated with the switch arm 50]) of the alarm relay.

Now that the circuit layout and various connections have been described in some detail, a description of the circuit operation will be presented.

Operation As mentioned earlier, the purpose of the signaling system shown in the drawing is to sound an alarm whenever a condition arises to which one or more of the detector means 90 is responsive, and to operate a fault indicator in the event that one or more of the circuit connections which run throughout the building becomes either opened or shorted. When initially placed in operation, the circuit-is balanced by varying the position of the wiper arm 62 of the potentiometer such that the magnetic force produced as a result of the current flowing through the balanced relay coil 56 is exactly counteracted by the magnetic force produced by the current flowing through the balanced relay coil 58. When these forces are balanced, the armature 64 is in the position shown such that the switch means 68 and 70 is in its normal first or standby position, as illustrated. If the current flowing through the balanced relay coil 56 decreases or the current Howing through the balanced relay coil 58 increases from that which exists when the system is in balance, the armature members 64 will rotate counterclockwise about the fulcrum 66 such that electrical continuity is established between the

contacts

68 and 74. When the armature 64 has been rotated in the counterclockwise direction such that

contacts

68 and 74 are closed and

contacts

70 and 76 are open, the circuit is said to be in its second or alarm position. Either an increase in the current flowing through the balanced relay coil 56 or a decrease in the current flowing through the balanced relay coil '58 causes the armature member 64 to rotate clockwise about the fulcrum 66 thereby causing

contacts

70 and 76 to close and contacts 68 and 74 to open. Under this condition, the switch means is said to be in its third or fault position.

When a source of line voltage is connected to the primary winding 12 of transformer 10, a voltage is developed across

secondary winding terminals

16 and 18 which is suflicient to energize the power failure relay 20. Energization of relay 20 causes electrical continuity to be established between the switch arm 20a and contact 24 and breaks the circuit between the

switch arms

20b and 20c and their

respective contacts

96 and 102. With electrical continuity established between contact 24 and switch arm 20a, a current path may be traced from the secondary winding terminal 16 through conductor 22 through the now closed switch contact 24, the conductor 26, to the junctions 28 and 3 2. At junction 28 a portion of the current which normally flows in the conductor 26 divides and passes through the resistor 52 and the main alarm 84 which is in parallel with resistor 52, through the balanced relay coil 56, and through the balancing potentiometer wiper arm 62 to junction 48. Likewise, at junction 32 a portion of the normal line current flowing in conductor 26 divides so that a fraction of the total current flows through the resistor 54 and the balance relay coil 58 and through the portion of the balancing potentiometer 60 to the right of the wiper arm 62 to a junction 48. Also, a supervisory current flows through the

detector lines

86 and 88 and the end of line resistor 92. In the absence of a dangerous condition or system fault,

the wiper arm 62 of the balancing potentiometer 60 can be set such that the currents flowing through the balanced relay coils 56 and 58 are substantially equal thereby producing equal magnetic forces on the armature 64 of the balanced relay. From junction 48 the current is returned to the secondary winding terminal 18 by way of conductor 42. With the

coils

56 and 58 exerting approximately equal forces on the armature member 64, the circuit is in the standby condition and both the fault alarm and the main alarm 84 are silent. Should a dangerous condition break out somewhere in the area being supervised, the normally open detector responds to this dangerous condition by closing its contacts thereby shorting out the

resistors

54 and 92. With these resistors shorted out, there is an increase in the amount of current which flows through the balanced relay coil 58 such that the coil 58 produces a greater magnetic force on the armature 64 than does the coil 56. As a result, the armature 64 is rotated in the counterclockwise direction so as to establish electrical continuity between the

contacts

68 and 74. As mentioned previously, this is the alarm position for the balanced relay armature. With contacts 68 :and 74 closed, a circuit path may be traced from the secondary winding terminal 16 through

conductors

22 and 26 to the junction 36. From junction 36 the current flows through the alarm relay coil 50 through the conductor 116 and the now closed

contacts

68 and 74, through the conductive armature 64 and the conductor 72 to junction 48. The current which flows through the relay coil 50 is returned from junction 48 to the secondary winding terminal 18 through conductor 42. The current flowing through the relay coil 50 causes a magnetic force to be produced which causes the

contact arms

50a, 50b and 50c to close against their

respective contacts

110, 118 and 114. The closure of the switch arm 5% against its associated contact 118 causes the alarm relay coil 50 to be locked in itsenergized position. The closure of the switch arm 50c against its associated contact 114 is effective to connect the main alarm 84 directly across the output of the secondary winding 14 so that sufficient current can now flow therethrough allowing it to sound. The closure of the alarm relay contact 50a against its associated contact 110 establishes a current path from the junction 36, through conductor 26 and the single pole double throw silencing switch 40, through conductor 78 and the fault alarm 80, through

conductors

82 and 108 to the conductor 42 which is connected to the secondary winding terminal 18. This current causes the fault alarm to sound. Once the occupant of the building hears the main alarm he knows that a dangerous condition exists.

Since the

lines

86 and 88 and the

lines

87 and 89 connecting the main alarm 84 to the control panel are strung throughout the building, most building codes require that these lines be supervised so that the occupant will be advised of a break in these lines. Assuming that a break does occur in either

line

86 or 88, the end of line resistor 92 would be disconnected so that it would no longer be in parallel with the resistor 54. The equivalent resistance in series with the balanced relay coil 58 therefore increases. As a result, less current now flows through the balanced relay coil 58 so that the magnetic force produced by this coil is outweighed by the magnetic force produced by the balanced relay coil 56. The armature member 64 therefore rotates in a clockwise direction about the fulcrum 66 causing electrical continuity to be established between the

contacts

70 and 76. Since the

contacts

68 and 74 are open when the armature 64 is in its third or fault position the alarm relay coil 50 remains deenergized. A current path may be traced, however, from the secondary winding terminal 16 through

conductors

22 and 26, through the silencing switch '40, through conductor 78 and the fault alarm 80, through conductor 82 and the now closed

contacts

70 and 76, through the armature 64 and conductor 72, back to the secondary Winding terminal '18 by way of conductor 42. It can be seen, then, that the fault alarm 80 is, under these circumstances, connected directly across the secondary winding of the transformer 10. Sufficient current therefore flows through the fault alarm to cause it to sound. Shouldthe sound from the fault alarm become objectionable to the occupant, once he has been advised that a fault exists he may silence this alarm by reversing the position of the switch arm 38 of the manual silencing switch 40 so as to connect the fault indicating lamp 98 directly across the secondary winding 14.

In a similar manner, if a fault should occur in the form of a short circuiting of the main alarm 84 the amount of current flowing through the balanced relay coil 56 will exceed that flowing through the balanced relay coil 58 again producing a clockwise rotation of the armature 64. As explained previously, this completes a circuit through the fault indicator 80' which will advise the occupant that a fault exists in the system so that he may take appropriate measures to correct the situation.

Still another fault which may occur is that the lines connecting the main alarm into the circuit may become open. Under this condition, the effective impedance in series with the balance relay coil 56 increases such that a greater magnetic force is applied to the armature 64 by the balanced relay coil 58 than is applied by the balanced relay coil 56. Armature member 64 therefore rotates counterclockwise to close the

contacts

68 and 74. This is the same as the alarm condition previously described. As already mentioned, when

contacts

68 and 74 close a current flows through the alarm relay 50 by way of

conductors

22, 26', 116, 72, and 42. With the alarm relay '50 energized its associated contacts 50a,

50b and 500 are pulled in. The closing of the'cont-act 50a against its associated contact 110 completes a circuit to connect the fault alarm directly across the output of the transformer 10. The closure of the contact arm 50c across its associated contact 114 would cause the main alarm 84 to ring, but since the fault which has been assumed is an open in the main alarm line, the main alarm 84 remains silent.

In the event of a power failure, no voltage will be induced in the secondary winding 14 of the transformer 10 so that the power failure relay 20 will become deenergized. With the power failure relay coil 20 deenergized its associated

contact arms

20a, 20b and 20c will assume the position illustrated in the drawing. When contact arm 20b closes against its associated contact 96 the auxiliary energy source 94- is connected between the junction 44 and conductor 42 and the conductor 26. Current therefore can flow from the positive terminal of the source 94 through the conductor 26 to the

junctions

28 and 32. As before, the current divides at these two points such that when no dangerous condition or fault (other than a power failure) exists, substantially equal currents will flow through the balanced relay coils 56 and 58 and through each half of the balancing potentiometer 60 and through conductor 42 back to the negative terminal of source 94. The armature 64 of the balanced relay therefore remains in its first or standby position. However, since the contact arm 200 of the power failure relay is now closed against its associated contact 102 a circuit path may be traced from the junction 32 through conductor 26, through the single pole double throw manual silencing switch 40, through the fault alarm 80 and

conductors

82, 104, and 100. In effect, then, the fault alarm 80 is connected directly across the energy source 94 and therefore sounds.

Should a dangerous condition arise during the power failure, one of the normally open condition responsive switches will close to short out the current limiting resistor 54 and the'end of line resistor 92. The current flowing through the balanced relay coil 58 therefore increases over the amount which normally flows and causes a counterclockwise rotation of the armature member 64. Current therefore flows from the auxiliary energy source 94 through the now closed contacts 96 and conductor 26 to the junction 36. From junction'36 the current continues to flow through the alarm relay coil 50, conductor 116, the now closed

contacts

68 and 74, and

conductors

72 and 42 back to junction 44 to which the energy source 94 is connected. With the alarm relay coil 50 energized, the

relay contacts

50a, 50b and 500 associated therewith close. When contact arm 50c closes against its associated contact 114 the main alarm 84 is connected directly across the energy source 94 so that it is able to sound.

Thus it can be seen that this circuit of this invention is effective to give an alarm to indicate the presence of a dangerous condition to which the detectors 90 are responsive, and to provide an indication to supervisory personnel in the event that a fault occurs in the system.

From the above description it will be apparent that I have produced a system apparatus which possesses all of the features that are set forth as desirable; and while I have described and illustrated what appears to be the preferred form of the invention, I reserve the right to make all changes within the spirit of the invention and without the ambit of the prior art.

I claim:

1. In a supervised condition detection and alarm apparatus, first alarm means for indicating the presence of an undesired condition, second alarm means for indicating the presence of circuit trouble, switch actuating means having a balanceable member normally held in a center position and controlled by a first and a second winding to close a first switch when said member moves in a first direction and to close a second switch when said member moves in an opposite direction, said first switch being closed when an output of said first winding produces to dominating force on said member, said second switch being closed when an output of said second winding produces the dominating force on said member, a source of power, a plurality of abnormal condition detector means, said detector means being normally open and connected in parallel, an end impedance connected adjacent a farthermost of said parallel detector means, a first resistance connected adjacent a closest of said detector means, circuit means including said first switch for connecting said second alarm to said source, circuit means including said second switch for connecting said first alarm to said source, circuit means including a parallel circuit of said first resistance, said end resistance and said parallel detectors for connecting said second winding to said source, a second resistance connected in parallel with said first alarm means, and circuit means comprising said second resistance for connecting said first winding to said source.

2, In a supervised condition detection and alarm apparatus, first alarm means for indicating the presence of an undesired condition, second alarm means for indicating the presence of an abnormal circuit, a source of power, switch actuating means having a balanceable member controlled by a first and a second Winding to close a first switch when said member moves in a first direction and to close a second switch when said member moves in an opposite direction, said first switch being closed to encrgize said second alarm means when said first winding produces to dominating force on said member, said second switch being closed to energize said first alarm means when said second winding produces the dominating force on said member, a plurality of parallel connected abnormal condition detector means, said detectors closing upon the presence of an undesired condition, an end resistance connected adjacent a farthermost parallel detector means, a first resistance connected adjacent a closest detector means, circuit means including a parallel circuit of said first resistance, said end resistance and said parallel detectors for connecting said second winding to said source, a second resistance connected in parallel with said first alarm means, and circuit means comprising said second resistance for connecting said first winding to said source.

3. In a supervised condition detection and alarm apparatus, first alarm means for indicating the presence of an abnormal condition, second alarm means for indicating the presence of an abnormal circuit, switch actuating means having a pivoted member controlled by a first and a second winding to close a first switch when said member moves in a first direction and to close a second switch when said member moves in an opposite direction, said first switch being closed when said first winding produces to dominating force on said member, said second switch being closed when said second winding produces the dominating force on said member, circuit means for adjusting the resultant etfect of the output of said windings on said member, a source of power, at least one normally open circuit abnormal condition detector means, a circuit termination means connected in parallel with detector means at one end of a circuit, a first resistance connected in parallel with detector means, circuit means including said first switch for connecting said second alarm to said source, circuit mean including said second switch for connecting said first alarm to said source, circuit means comprising two parallel conductors connecting said first resistance, said termination means and said detector in parallel for connecting said second winding to said source, a second resistance connected in parallel with said first alarm means, and circuit means comprising said second resistance for connecting said first winding to said source.

4. In a supervised condition detection and alarm apparatus, first alarm means for indicating the presence of an undesired condition, second alarm means for indicating the presence of circuit trouble, switch actuating means having a balanceable member controlled by an output of a first and a second actuator Winding to close a first switch when said member moves in a first direction and to close a second switch when said member moves in an opposite direction, said first switch being closed when said output of said first winding produces to dominating force on said member, said second switch being closed when said output of said second Winding produces the dominating force on said member, a source of power, a plurality abnormal condition detector means, said detector means being normally open and connected in parallel, an end resistance connected adjacent a farthermost of said parallel detector means, a first resistance connected adjacent a closest of said detector means, circuit means including said first switch for connecting said second alarm to said source, circuit means including said second switch for connecting said first alarm to said source, voltage balancing circuit means, circuit means including a parallel circuit of said first resistance, said end resistance, said parallel detectors and said voltage balancing circuit means for connecting said second winding to said source, a second resistance connected in parallel with said first alarm means, and circuit means comprising said second resistance for connecting said first winding to said source.

References Cited in the file of this patent UNITED STATES PATENTS 2,074,262 Grant Mar. 16, 1937 2,728,904 Schafer Dec. 27, 1955 2,891,240 Rohulich June 16, 1959